This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This research aims to provide experimental data in support of experimental and theoretical approaches for predicting non-specific biomolecular interactions within Hepatitis B virus (HBV) nucleocapsids that underpin the viral capsid formation and stability. Small-angle x-ray scattering measurements will be carried out on mature, pregenomic and empty nucleocapsids. These will be used synergistically and iteratively with modeling to provide for data interpretation and model optimization and verification. The proposed research aims to solve the internal microscopic structure of nucleocapsids including the distributions of encapsidated nucleic acids and unstructured protein domains and provide a basis to understand viral assembly. The first measurements will provide a base line for later scattering experiments and modeling on nucleocapsids, biochemicaly and genetically modified nucleocapsids to provide information on HBV morphogenesis. The scattering and theoretical analysis will in turn frame future biochemical and genetic approaches to regulate and ultimately eradicate HBV infection.